This invention relates to heating devices and more particularly to a device for attaching modular electronic components to or removing them from a substrate such as a printed circuit board.
Present day devices for removing or installing modular electronic components from a substrate such as a printed circuit board generally fall into two categories: those which use a heated head which contacts each terminal to melt the solder thereon or those which use a blast of hot air to melt the solder. The former devices are generally very complex and employ a heated head having a plurality of spaced apart fingers each of which must be precisely aligned with each terminal around the component to simultaneously heat the solder on it. The component is then withdrawn from the substrate by vacuum suction or other mechanical means. The procedure is reversed for installing a component. An example of such a device is disclosed in U.S. Pat. No. 3,382,564. A major disadvantage of this type of device is that, due to the ever-increasing miniaturization of electronic systems and individual components in them, the terminals of such components are extremely close together thus making precise alignment of the fingers of the heating head therewith extremely difficult. Improper alignment or contact often results in solder flowing between terminals on the component thus shorting them or otherwise damaging them. The latter devices direct a blast of hot air at the terminals from a source above the component to simultaneously melt the the solder on each. Such a device, for example, is set forth in U.S. Pat. No. 4,366,925. Such a device may function satisfactorily if there is a large spacing between component from above will not spill over and melt the solder on the terminals of adjacent components. However, as aforementioned, not only are the components themselves becoming increasingly smaller but their proximity on the printed circuit substrate is also increasing. Thus, there is a need for a device which cannot only provide a closely controlled and evenly distributed source of heat sufficient to melt solder associated with component terminals or printed substrate conductors during installation or removal of the electronic component relative thereto but one which can rapidly and precisely direct this controlled heat where desired thereby minimizing the likelihood of melting the solder on the terminals of adjacent components or otherwise damaging the printed conductors on the substrate. There is also a need for a device of the subject type which has the capability of precisely positioning the electronic component and its terminals on the ends of the printed conductors on the substrate to insure no overlapping as well as removing the component to insure that no liquid solder is smeared on the substrate between the conductors printed thereon.
There is a further need for a device of the subject type which is capable of applying additional heat to those terminals of an electronic component which are connected to a ground plane or a voltage supply layer of a multi-layer printed circuit board. That is, a ground plane or voltage supply layer generally constitutes a continuous sheet which, in effect, constitutes a heat sink. Thus more heat must be applied to a terminal connected to such a sheet in order to melt the solder therefrom.
It is therefore the primary object of the present invention to provide a superior device for installation and removal of electronic components from circuits printed on a substrate.
It is a further object of this invention to provide a device of the subject type which is capable of applying additional heat to terminals connected to ground planes and the like.